I. Field of the Invention
This invention relates to battery jumper cables in general, and more specifically to battery jumper cables specifically designed to operate only when the polarity and voltages of the primary and secondary batteries meet certain minimum requirements.
II. Description of the Prior Art
Most people are aware of the problems encountered when a rechargeable storage battery, such as batteries used on automobiles, trucks, tractors, lawn mowers etc., discharge and are then unable to supply the electrical energy required to start and/or run the engine. The typical solution to this problem is to provide another well-charged storage battery and then to connect this secondary battery in parallel with the original battery so as to supply the electrical energy required to start the engine. Typically the engine includes an alternator or generator which then will recharge the previously discharged storage battery.
With the proliferation of non-technically inclined motor vehicle operators, such as women and the elderly, the present inventor has felt a strong demand for a jumper cable system which eliminates most of the guesswork, uncertainty and danger from this jumper-starting procedure. For example, it is often difficult to clearly ascertain the polarity of the terminals on extremely old batteries with corrosion present adjacent the terminals, on batteries on which the terminals are not clearly marked, and the new side-terminal batteries.
The dangers and uncertainties of using normal straight-through battery jumper cables are legendary. For example, it is not unusual for a technically unskilled person to ruin a good battery by coupling it with reversed polarity to another slightly discharged battery. Also, a good battery may be destroyed by coupling it in parallel with a storage battery which contains an internal short-circuit. It is also not unusual in these situations to cause catastrophic failures in automotive alternators when the primary battery is being furnished with a supplemental charge when the two batteries are being coupled together. Furthermore, recent safety studies indicate that under some conditions the discharged battery may explode from internal disorders, or from the ignition of standing discharge gases which collect immediately adjacent to the cells of the battery by a spark produced by connecting the jumper cables and the fully charged battery to the terminals of the discharged battery.
The present inventor is unaware of any devices or systems which reduce or eliminate these problems. Basch, in U.S. Pat. No. 1,246,038, discloses a protective device for electrical distribution systems in which insulated cables are employed as transmission conductors. This system dis-connects from the distribution system a faulty section of the cable before the remainder of the distribution system is damaged from the abnormal conditions arising from the fault. McNeil, in U.S. Pat. No. 2,031,784, discloses a system designed to be interconnected with a storage battery and a battery charger. This system is designed to eliminate reverse current between the battery and generator and to prevent the discharging of the battery when the voltage of the generator becomes less than the voltage of the battery. Ball, in U.S. Pat. No. 3,369,164, discloses a device for preventing reverse direction recharging of a discharged secondary battery. This system relates to a magnetically activated reed switch for electrically shorting a discharged secondary cell so as to shunt substantially all of the discharged current of cooperatively associated secondary cells around the discharged cell. None of these disclosures are similar to the design and concept of the present invention. None of these references employ voltage and polarity comparators which indicate or control the operation of a series connected contactor which enables the flow of electrical energy from one battery to another.